Retention catheter

ABSTRACT

A retention catheter comprising concentric, relatively shiftable tubes adapted to be inserted into the urethra. A deformable stretch interconnects the distal ends of the tubes and is deformable to an enlarged, preselected retention configuration wherein the stretch engages the wall of the urinary bladder in order to hold the catheter in position. Relative axial shifting of the inner and outer tubes deforms the stretch from said retention configuration to a collapsed configuration wherein the stretch lies entirely inside the outer tube in order to facilitate removal of the catheter. The catheter is constructed to permit irrigation of the urethra while inserted therewithin.

Summers [451 Apr. 30, 1974 RETENTION CATHETER [76] Inventor: David P.Summers, 475 Northaven Dr., Overland Park, Kans. 94015 [22] Filed: Jan.17, 1972 [21] Appl. No.: 218,233

[52] US. Cl. 128/349 R [51] Int. Cl A6lm 25/00 [58] Field of Search128/348-350, 128/345 [56] References Cited UNITED STATES PATENTS2,649,092 8/1953 Wallace 128/349 R 3,241,554 3/1966 Coanda 128/3453,344,791 10/1967 Foderick... 128/349 R 3,050,066 8/1962 Koehn 128/349 B3,053,257 9/1962 Birthwell 128/349 B 3,394,705 7/1968 Abramson.....128/349 B 3,593,713 7/1971 Bogoff et a1 128/349 B FOREIGN PATENTS ORAPPLICATIONS 955,490 4/1964 Great Britain 128/349 R PrimaryExaminer-Charles F. Rosenbaum Attorney, Agent, or Firm-Schmidt, Johnson,Hovey & Williams 7] ABSTRACT A retention catheter comprising concentric,relatively shiftable tubes adapted to be inserted into the urethra. Adeformable stretch interconnects the distal ends of the tubes and isdeformable to an enlarged, preselected retention configuration whereinthe stretch engages the wall of the urinary bladder in order to hold thecatheter in position. Relative axial shifting of the inner and outertubes deforms the stretch from said retention configuration to acollapsed configuration wherein the stretch lies entirely inside theouter tube in order to facilitate removal of the catheter. The catheteris constructed to permit irrigation of the urethra while insertedtherewithin.

18 Claims, 4 Drawing Figures PATENTEDAFR-w m4 Ill-l Ill-v.

1 RETENTION CATHETER This invention relates to catheters of the typeadapted'to be retained within a cavity of the body, such as the urethra,and presenting a path for fluid flow either into or out of the cavity.

Retention catheters of the class described usually include a tubularmember that is inserted inside a cavity of the body through an incisionor natural opening, a common use being insertion of the catheter intothe urinary bladder through the urethra. One form of such catheter has aweakened wall portion that ispositioned inside the bladder or other bodycavity, and a passage inside the tube through which distilled water isfed under pressure to cause expansion of the weakened wall portion andform an enlarged section that acts to retain the catheter in position.Occasionally it becomes necessary to remove such catheters, due eitherto loss of muscle tone over a prolonged period which may result inleakage around the catheter and through the urethral canal, or due toclogging of the catheter itself. It is also occasionally necessary toremove the catheter in order t'ocleanse the urethral canal and preventbuildup of mucoserous matter within the urethra which can lead tosubsequent infection.

A major problem associated with a pressurized type catheter, as well asretention catheters in general, is the unreliability of the enlargedretention section of the catheter in completely collapsing to a minimumdimensional configuration which would facilitate the easiest and leastpainful removal of the catheter from the urethra. In the hydraulicallypressurized type retention catheter described, for instance, thepressurized fluid passage which communicates with theenlarged retentionsection of the catheter may become clogged or pinched off by depositsbuilt up inside the urethra or the catheter. The pressurized fluidcannot then be released from the enlarged retention section at all, orin less severe .cases all of the fluid from the enlarged retentionsection cannot be drained, so that the section will notcollapse'completely. In such instance the only recourse for removing thecatheter has been to overpressurize the enlarged retention section untilit destructively bursts inside the urinary bladder, thereupon requiringcomplete and thorough cleansing of the bladder in order to remove allparts of the destroyed catheter.

Leakage of the water from the pressurized retention section by osmoticprocesses over a substantial period of time, or simply leakage bymalfunction of the catheter, will cause a collapse of the enlargedsection and otherwise detract from the suitability of the catheter forits intended use. Yet another problem is that the expansion of thepressurized fluid carrying passage inside the catheter drasticallyconstricts the size of the catheter drainage path that runs generallyparallel to the pressurized passage, and curtails both ingressive anddrainage flow from the bladder or other body cavity.

It is an important object of the present invention to provide aretention catheter having a section which is deformable to an enlargedretention configuration without pressurizing said section so as toeliminate the above-described problems associated with pressurizedretention catheters. I

It is another important object of the invention to provide a retentioncatheter which is positively, reliably and completely collapsible fromits retention configuration to a configuration facilitating the easiestand least painful removal of the catheter under all conditions.

Another important object of the present invention is to provide acatheter provided with means permitting irrigation of the urethral canalwith fluid while the catheter is in its inserted position within theurethra to inhibit buildup of mucoserous matter therewithin.

Another object of the invention is to provide a retention catheterhaving a large nonconstricting, interior path capable of conductingsubstantially greater flow volumes to and from the body cavity than canother types of retention catheters.

A more particular object of the present invention is to provide aretention catheter characterized by the foregoing objects which includesa pair of interconnected, relatively shiftable inner and outer tubesthat can be inserted into the urethra to present a path for conductingurine from the bladder, and a stretch of deformable material attached tothe distal end of one of the tubes, which stretch is deformable betweena col- These and other objects and advantages of the present inventionare particularly set forth in or will become apparent from the followingdetailed description of a preferred embodiment of the invention whenread in conjunction with the accompanying drawing, wherein:

FIG. 1 is a longitudinal elevation of a catheter constructed inaccordance with the present invention with the proximal end of the innershaft being shown in cross section, the catheter being illustrated inits inserted disposition within the urethral canal;

FIG. 2 is a partial longitudinal central section of fragmentary portionsof the catheter when in its collapsed configuration;

FIG. 3 is a view similar to FIG. 2 except that the catheter is disposedin its enlarged retention configuration; and

FIG. 4 is a transverse cross-sectional view taken along lines 4-4 ofFIG. 2.

Referring now more particularly to the several figures of the drawing,there is illustrated a retention catheter, generally denoted by thenumeral 10, which is an integral one-piece unit made of a medical-gradesilicon elastomer material such as SILASTIC, a registered trademark ofDow Corning Corporation, or other siliconized plastic or medical-gradelatex material. Catheter 10 is comprised of concentric, telescoping,inner and outer tubes 12 and 14, and a stretch 16 that is secured insealing relationship to the distal ends 18 and 20 of the inner and outertubes respectively. The particular catheter illustrated is designed forinsertion through the urethra 22 into the urinary bladder cavity 42 of ahuman body as shown'in FIG. 1. It will be noted, however, that thepresent invention may be advantageously used for insertion through othernatural orifices or incisions into different cavities of the body.

Hollow outer tube 14- is substantially longer than the urethral canal 22into which the outer tube is to be in- -within the urethra 22 when thecatheter is inserted as shown in FIG. 1. Hollow inner tube 12 is of adiameter slightly smaller than the outer tube so as to define an annularspace 26 between the inner and outer tubes, annular space 26 beingclosed and sealed at the distal end of the catheter by stretch 16 andbeing open at its opposite end adjacent the proximal end 28 of outertube 14. Interior 30 of inner tube 12 is open both at the distal end 18and at the proximal end 32 of tube 12 where there is provided a flaringfunnel section 34.

The deformable nature of stretch 16 which interconnects inner and outertubes 12 and 14 permits axial shifting of the tubes relative to eachother. The walls of stretch 16 are substantially thinner than the wallsof either inner tube 12 or outer tube 14 so that upon relativelyshifting the inner and outer tubes, stretch 16, rather than the tubesthemselves, will deform. Stretch 16 is illustrated in its collapsedconfiguration in FIG. 2 wherein it is disposed radially inwardly of theouter tube and, preferably, folded back completely inside the outer tube14. Stretch 16 is also expansible to an enlarged retention configurationas illustrated in FIG. 3 wherein the stretch is in a bulbous or cup-likeshape of maximum diameter substantially greater than the diameter ofouter tube 14. In its retention configuration, stretch 16 defines asegment 36 that extends radially outwardly from distal end 20 of theouter tube, as well as a second segment 38 that extents generallyaxially from the outer end of segment 36 up to distal end 18 of innertube 12.

In operation, catheter I is readied for insertion or removal from theurethra upon deforming stretch 16 to its collapsed configuration byshifting inner tube 12 axially relative to outer tube 14 to the positionillustrated in FIG. 2 wherein distal end 18 of the inner tube is locatedinside outer tube 14 and generally rearwardly of the distal end 20 ofthe outer tube. Stretch 16 is thereby located radially inside outer tube14, i.e., radially inside an imaginary cylinder formed by an axialprojection of outer tube 14, to minimize the maximum diameter ofcatheter l0 and thus facilitate the easiest and least painful travel,either in insertion or removal, of the catheter along urethra 22.

With stretch 16 in its collapsed configuration, the catheter is insertedinto the urethra until the distal end 20 of outer tube 14 lies insidethe interior wall 40 of the urinary bladder and within interior cavity42 thereof. While holding outer tube 14 substantially stationary withinurethra 22 to minimize pain, inner tube 12 is shifted axially relativeto the outer tube, rightwardly as viewed in various figures, to a secondposition shown in FIG. 3, wherein the distal end 18 of inner tube 12 islocated axially outwardly (rightwardly) of the outer tube distal end 20.Tube interior 30 is in direct communication with the interior cavity 42of the bladder so as to present a path for draining urine therefrom outfunnel 34 at the proximal end 32 of the inner tube 12. The relativelylarge diameter of interior 30, along with the lack of forces exertedupon the exterior surface of inner tube 12 that would tend to constrictthe latter, permits approximately three times greater flow of fluidthrough interior 30 than can pass through the internal passage of othertypes of catheters.

The shifting of inner tube 12 from its FIG. 2 to its FIG. 3 positiondeforms and pushes stretch 16 outwardly of the distal end 20 of theouter tube and into the urinary bladder interior cavity 42. When freefrom the inside of outer tube 14, stretch 16 quickly expands or pops outto its preselected retention configuration as illustrated in FIG. 3.Segment 36 is then disposed to engage the bladder wall 40 and therebyretain and hold the entire catheter 10in its desired, inserteddisposition as shown in FIG. 1.

Stretch 16 is sufficiently yieldable so as to deform between thecollapsed and retention configurations as desired, yet is alsosufficiently rigid in nature so as to hold its shape, at least when inthe retention configuration, in opposition to the normal stresses andforces that the stretch encounters when located within the bladder. Thisself-holding property of stretch l6 assures that the stretch will resistunwanted relative shifting of the inner and outer tubes, as well aspositively hold the catheter in its inserted disposition, at least untilthe inner tube is again deliberately shifted to deform stretch 16.

Over a period of time there will be build up of mucoserous matter alongthe urethra 22 generally outside of outer tube 14. To alleviate thisproblem, the catheter of the present invention is constructed so thatcleansing fluid may be introduced through the open end of annular space26 adjacent the proximal end 28 of outer tube 14. Stretch 16 acts as abarrier and effectively seals one end of annular space 26 from both thebladder interior cavity 42 as well as the urine-conducting interior 30of the inner tube, so that the fluid introduced into annular space 26may flow out aperture 24 to irrigate the urethral canal and drainmucoserous matter therefrom without removing the catheter from urethra22. Alternately, the urine itself may be used as the irrigating fluid byopening the inner end of annular space 26 such as by slitting orperforating stretch 16, and by placing a nonporous barrier across theend of space 26 adjacent outer tube end 28. The urine then flows intoannular space 26 and out apertures 24 to irrigate urethra 22.

When it is desired'to remove the catheter from urethra 22, inner tube 14can be shifted back leftwardly from its FIG. 3 to its FIG. 2 position tothereby pull and deform, without fail, the stretch 16 back to itscompletely collapsed configuration of FIG. 2. Accordingly, catheter 10can then be removed from the urethra in as easy a manner as it wasinserted. The loose, nonengaging disposition of inner tube 12 withinouter tube 14 assures that inner tube 12 will be free to shift with caseback to its FIG. 2 position, with the only force resisting such leftwardshifting of the inner tube being that which is required to deformstretch 16 back to its collapsed configuration.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. A retention catheter comprising:

relatively shiftable, inner and outer tubes adapted to be inserted inthe urethra to present a path for conducting urine from the bladder; and

a stretch of pliant material interconnecting the distal ends of saidtubes to present said catheter as an integral one-piece unit in whichthe tubes and said stretch are of like material,

said stretch being molded to independently and automatically assume aself-formed pre-determined shape presenting an enlarged retentionconfiguration wherein a segment of the stretch is adapted to engage thewall of .the bladder to hold the catheter when in its inserteddisposition, with said inner tube in direct communication with thebladder,

said stretch being deformable from said shape to a collapsedconfiguration for facilitating travel of the catheter along the urethra,

said stretch respectively deforming to said collapsed configuration andassuming said retention configuration solely in response to shifting ofsaid tubes to first and second positions relative to each other.

2. A retention catheter comprising:

interconnected, relatively shiftable, inner and outer tubes adapted tobe inserted in the urethra to present a path for conducting urine fromthe bladder; and

a stretch of pliant material attached to the distal end of one of saidtubes, said stretch being molded to independently and automaticallyassume a selfformed pre-determined shape presenting an enlargedretention configuration wherein a segment of the stretch is adapted toengage the wall of the bladder to hold the catheter when in its inserteddisposition,

said stretchbeing deformable from said shape to a collapsedconfiguration for facilitating travel of the catheter along the urethra,

said stretch respectively deforming to said collapsed configuration andassuming said retention configuration solely in response to shifting ofsaid tubes to first and second positions relative to each other,

said stretch being attached to and interconnecting the distal ends ofboth of said tubes.

3. A catheter as set forth in claim 2, wherein said stretch is nonporousand seals the annular space between said inner and outer tubes from thebladder and the interior of said inner tube, said interior presentingsaid path for conducting urine from the bladder.

4. A catheter as set forth in claim 2, substantially the entirety ofsaid stretch being disposed radially inwardly of said outer tube when insaid collapsed configuration.

5. A catheter as set forth in claim 4, said stretch hav- I ing saidsegment disposed radially outwardly of said outer tube and to engage thebladder wall when said stretch is in said retention configuration.

6. A catheter as set forth in claim 5, said inner tube being axiallyshiftable within the outer tube to said first and second'positions whilesaid outer tube remains substantially stationary within the urethra.

7. A catheter as set forth in claim 6, wherein shifting of said innertube to said first position locates said distal end thereof inside theouter tube and locates said stretch completely inside said outer tube.

8. A catheter as set forth in claim 7, wherein shifting said inner tubeto said second position locates said distal end thereof axially outsidesaid outer tube and locates said stretch with said segment thereofflaring radially outwardly from said distal end of the outer tube andwith a second segment of the stretch extending generally axially fromthe first segment to said distal end of the inner tube.

9. A catheter as set forth in claim 2, said stretch being sufficientlyrigid to be self-holding in said retention configuration and to resistsaid relative shifting of said tubes and hold the catheter in itsinserted disposition when said stretch is in said retentionconfiguration.

said tubes-effects said deformation of said stretch without deformingsaid tubes.

11. A catheter as set forth in claim 10, said unit being of siliconeelastomer material having a memory.

12. A catheter, comprising:

spaced, relatively shiftable inner and outer tubes adapted to beinserted in the urethra, the interior of said inner tubepresenting apath for conducting urine from the bladder; and

a barrier of nonporous material interconnecting said inner and outertubes to seal one end of the annular space between said inner and outertubes, the other end of said annular'space being open to permitintroduction of fluid thereinto,

said outer tube being perforated whereby introduction of fluid into saidannular space effects irrigation of the urethra while the catheter is inits inserted disposition.

13'. A catheter as set forth in claim 12,

said barrier being a stretch interconnecting the distal ends of saidinner and outer tubes to seal said annular space from the bladder andsaid interior of the inner tube, said catheter being adapted to receivefluid from an external source through said other end of the annularspace to irrigate the urethra.

14. A retention catheter adapted to be inserted through an opening in ahuman body into a cavity of the body, said catheter comprising:

relatively shiftable, inner and outer tubes adapted to be insertedthrough the opening to present a path for conducting fluid to and fromthe cavity; and

a stretch of pliant material interconnecting the distal ends of saidtubes to present said catheter as an integral, one-piece unit in whichthe tubes and said stretch are of like material,

said stretch being molded to independently and automatically assume aself-formed, predetermined shape presenting an enlarged retentionconfiguration wherein a segment of the stretch is adapted to engage thewall of the cavity to hold the catheter when in its inserted dispositionwith said inner tube in direct communication with the cavity,

said stretch being deformable from said shape to a collapsedconfiguration for facilitating travel of the catheter along the opening,

said stretch respectively deforming to. said collapsed configuration andassuming said retention configuration solely in response to shifting ofsaid tubes to first and second positions relative to each other.

15. A catheter as set forth in claim 14 wherein said material is of thetype having a memory, said stretch spontaneously assuming said shapewhen said tubes are shifted to said second position.

16. A retention catheter adapted to be inserted through an opening in ahuman body into a cavity of the body, said catheter comprising:

interconnected, relatively shiftable, inner and outer tubes adapted tobe inserted through the opening to present a path for conducting fluidto and from the cavity; and

a stretch of pliant material attached to the distal end of one of saidtubes, said stretch being molded to independently and automaticallyassume a selfformed, predetermined shape presenting an enlargedretention configuration wherein a segment of the stretch is adapted toengage the wall of the cavity to hold the catheter when in its inserteddisposition,

said stretch being deformable from said shape to a collapsedconfiguration for facilitating travel of the catheter along the opening,

said stretch respectively deforming to said collapsed configuration andassuming said retention configuration solely in response to shifting ofsaid tubes to first and second positions relative to each other, saidmaterial being of the type having a memory, said stretch spontaneouslyassuming said shape when said tubes are shifted to said second position,said tubes and said stretch being integral to present a one-piece unit,

said stretch being disposed interiorly of said outer tube when saidtubes are in said first position and disposed exteriorly of said outertube when said tubes are in said second position.

17. A catheter as set forth in claim 16 wherein said stretch isstretched axially along the interior of said outer tube when disposedinteriorly thereof.

18. A retention catheter comprising:

interconnected, relatively shiftable, inner and outer tubes adapted tobe inserted in the urethra to present a path for conducting urine fromthe bladder; and

a stretch of deformable material attached to the distal end of one ofsaid tubes, said stretch being deformable to a collapsed configurationfacilitating travel of the catheter along the urethra and beingdeformable to an enlarged retention configuration wherein a segment ofthe stretch is adapted to engage the wall of the bladder to hold thecatheter in its inserted disposition,

said stretch deforming respectively to said collapsed and retentionconfigurations in response to shifting of said tubes to first and secondpositions relative to each other,

said stretch being attached to and interconnecting the distal ends ofboth of said tubes,

said stretch being nonporous and sealing the annular space between saidinner and outer tubes from the bladder and the interior of said innertube, said interior presenting said path for conducting urine from thebladder,

said outer tube being perforated whereby introduction of fluid into saidannular space effects irrigation of the urethra while the catheter is inits inserted disposition.

3,807 ,408 Dated April 30, 1974 Patent No.

David P Summers Inventor(s) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

' On the cover sheet I76] "Overland, Park, Kans,"

should read Daly City, Calif.

' (SEAL) Attest:

McCOY M. GIBSON JR. Attesting Officer C. MARSHALL DANN Commissioner ofPatents FQRM PO-OSO (to-69) USCOMM-DC eos7e-r=e9 U.S GOVERNMENT PRINTINGOFFICE: 5 93 o

1. A retention catheter comprising: relatively shiftable, inner andouter tubes adapted to be inserted in the urethra to present a path forconducting urine from the bladder; and a stretch of pliant materialinterconnecting the distal ends of said tubes to present said catheteras an integral one-piece unit in which the tubes and said stretch are oflike material, said stretch being molded to independently andautomatically assume a self-formed pre-determined shape presenting anenlarged retention configuration wherein a segment of the stretch isadapted to engage the wall of the bladder to hold the catheter when inits inserted disposition, with said inner tube in direct communicationwith the bladder, said stretch being deformable from said shape to acollapsed configuration for facilitating travel of the catheter alongthe urethra, said stretch respectively deforming to said collapsedconfiguration and assuming said retention configuration solely inresponse to shifting of said tubes to first and second positionsrelative to each other.
 2. A retention catheter comprising:interconnected, relatively shiftable, inner and outer tubes adapted tobe inserted in the urethra to present a path for conducting urine fromthe bladder; and a stretch of pliant material attached to the distal endof one of said tubes, said stretch being molded to independently andautomAtically assume a self-formed pre-determined shape presenting anenlarged retention configuration wherein a segment of the stretch isadapted to engage the wall of the bladder to hold the catheter when inits inserted disposition, said stretch being deformable from said shapeto a collapsed configuration for facilitating travel of the catheteralong the urethra, said stretch respectively deforming to said collapsedconfiguration and assuming said retention configuration solely inresponse to shifting of said tubes to first and second positionsrelative to each other, said stretch being attached to andinterconnecting the distal ends of both of said tubes.
 3. A catheter asset forth in claim 2, wherein said stretch is nonporous and seals theannular space between said inner and outer tubes from the bladder andthe interior of said inner tube, said interior presenting said path forconducting urine from the bladder.
 4. A catheter as set forth in claim2, substantially the entirety of said stretch being disposed radiallyinwardly of said outer tube when in said collapsed configuration.
 5. Acatheter as set forth in claim 4, said stretch having said segmentdisposed radially outwardly of said outer tube and to engage the bladderwall when said stretch is in said retention configuration.
 6. A catheteras set forth in claim 5, said inner tube being axially shiftable withinthe outer tube to said first and second positions while said outer tuberemains substantially stationary within the urethra.
 7. A catheter asset forth in claim 6, wherein shifting of said inner tube to said firstposition locates said distal end thereof inside the outer tube andlocates said stretch completely inside said outer tube.
 8. A catheter asset forth in claim 7, wherein shifting said inner tube to said secondposition locates said distal end thereof axially outside said outer tubeand locates said stretch with said segment thereof flaring radiallyoutwardly from said distal end of the outer tube and with a secondsegment of the stretch extending generally axially from the firstsegment to said distal end of the inner tube.
 9. A catheter as set forthin claim 2, said stretch being sufficiently rigid to be self-holding insaid retention configuration and to resist said relative shifting ofsaid tubes and hold the catheter in its inserted disposition when saidstretch is in said retention configuration.
 10. A catheter as set forthin claim 9, said inner and outer tubes and said stretch being integraland presenting a one-piece unit, the wall thickness of said stretchbeing substantially less than the wall thicknesses of said inner andouter tubes whereby said relative shifting of said tubes effects saiddeformation of said stretch without deforming said tubes.
 11. A catheteras set forth in claim 10, said unit being of silicone elastomer materialhaving a memory.
 12. A catheter, comprising: spaced, relativelyshiftable inner and outer tubes adapted to be inserted in the urethra,the interior of said inner tube presenting a path for conducting urinefrom the bladder; and a barrier of nonporous material interconnectingsaid inner and outer tubes to seal one end of the annular space betweensaid inner and outer tubes, the other end of said annular space beingopen to permit introduction of fluid thereinto, said outer tube beingperforated whereby introduction of fluid into said annular space effectsirrigation of the urethra while the catheter is in its inserteddisposition.
 13. A catheter as set forth in claim 12, said barrier beinga stretch interconnecting the distal ends of said inner and outer tubesto seal said annular space from the bladder and said interior of theinner tube, said catheter being adapted to receive fluid from anexternal source through said other end of the annular space to irrigatethe urethra.
 14. A retention catheter adapted to be inserted through anopening in a human body into a cavity of the body, saiD cathetercomprising: relatively shiftable, inner and outer tubes adapted to beinserted through the opening to present a path for conducting fluid toand from the cavity; and a stretch of pliant material interconnectingthe distal ends of said tubes to present said catheter as an integral,one-piece unit in which the tubes and said stretch are of like material,said stretch being molded to independently and automatically assume aself-formed, predetermined shape presenting an enlarged retentionconfiguration wherein a segment of the stretch is adapted to engage thewall of the cavity to hold the catheter when in its inserted dispositionwith said inner tube in direct communication with the cavity, saidstretch being deformable from said shape to a collapsed configurationfor facilitating travel of the catheter along the opening, said stretchrespectively deforming to said collapsed configuration and assuming saidretention configuration solely in response to shifting of said tubes tofirst and second positions relative to each other.
 15. A catheter as setforth in claim 14 wherein said material is of the type having a memory,said stretch spontaneously assuming said shape when said tubes areshifted to said second position.
 16. A retention catheter adapted to beinserted through an opening in a human body into a cavity of the body,said catheter comprising: interconnected, relatively shiftable, innerand outer tubes adapted to be inserted through the opening to present apath for conducting fluid to and from the cavity; and a stretch ofpliant material attached to the distal end of one of said tubes, saidstretch being molded to independently and automatically assume aself-formed, predetermined shape presenting an enlarged retentionconfiguration wherein a segment of the stretch is adapted to engage thewall of the cavity to hold the catheter when in its inserteddisposition, said stretch being deformable from said shape to acollapsed configuration for facilitating travel of the catheter alongthe opening, said stretch respectively deforming to said collapsedconfiguration and assuming said retention configuration solely inresponse to shifting of said tubes to first and second positionsrelative to each other, said material being of the type having a memory,said stretch spontaneously assuming said shape when said tubes areshifted to said second position, said tubes and said stretch beingintegral to present a one-piece unit, said stretch being disposedinteriorly of said outer tube when said tubes are in said first positionand disposed exteriorly of said outer tube when said tubes are in saidsecond position.
 17. A catheter as set forth in claim 16 wherein saidstretch is stretched axially along the interior of said outer tube whendisposed interiorly thereof.
 18. A retention catheter comprising:interconnected, relatively shiftable, inner and outer tubes adapted tobe inserted in the urethra to present a path for conducting urine fromthe bladder; and a stretch of deformable material attached to the distalend of one of said tubes, said stretch being deformable to a collapsedconfiguration facilitating travel of the catheter along the urethra andbeing deformable to an enlarged retention configuration wherein asegment of the stretch is adapted to engage the wall of the bladder tohold the catheter in its inserted disposition, said stretch deformingrespectively to said collapsed and retention configurations in responseto shifting of said tubes to first and second positions relative to eachother, said stretch being attached to and interconnecting the distalends of both of said tubes, said stretch being nonporous and sealing theannular space between said inner and outer tubes from the bladder andthe interior of said inner tube, said interior presenting said path forconducting urine from the bladder, said outer tube being perforatedwhereby introduction oF fluid into said annular space effects irrigationof the urethra while the catheter is in its inserted disposition.